In Land Mobile Radio (LMR) communication systems, a mobile device monitors a control channel, for example for group call activity, such as talkgroup calls. For radios that have fallen back to Long Term Evolution (LTE) systems, a mobile radio goes to idle state after ten seconds of inactivity.
If a new talkgroup call is started, an idle mobile radio that is on the LTE system and in the talkgroup needs to be paged and switched from idle mode to connected mode. In current systems, the paging cycle is 1.28 seconds. If the initial page fails, a nationwide page is required to attempt to locate the mobile radio. This adds additional time, perhaps up to several seconds, until the radio is in connected mode and part of the call. To avoid audio truncation of the start of the audio of the talkgroup call, the audio is typically not sent until all talkgroup radios are in connected mode. Such a delay is unacceptable for missions critical use cases.
Therefore, a need exists for a method and system to begin talkgroup calls immediately without having audio truncation. Further, a need exists to start talkgroup calls immediately with audio truncation and without draining the batteries of mobile devices that are part of the talkgroup.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.